1. Institute of Physics, University of Brasília, 70910-900 Brasília, Brazil
2. Computational Materials Laboratory, LCCMat, Institute of Physics, University of Brasília, 70910-900 Brasília, Brazil
3. Department of Electrical Engineering, Faculty of Technology, University of Brasília, 70910-900 Brasília, Brazil
4. Applied Physics Department, Gleb Wataghin Institute of Physics, University of Campinas, 13083-859 Campinas, São Paulo, Brazil